Summary: The popular marketing tool PixelYourSite version 10.1.1.1 has been found to contain a critical security vulnerability due to the way it handles user input. An attacker could exploit this vulnerability to execute arbitrary code, potentially leading to data compromise or unauthorized control over the affected server. In this detailed post, we will explore the vulnerability's key aspects, including its root cause, exploit details, and possible mitigation strategies.

Background

PixelYourSite is a widely-used plugin that makes it easy for website operators to manage their Facebook and Google Ads accounts, as well as custom JavaScript codes. The plugin helps businesses track e-commerce events, user activity, and dynamic remarketing more efficiently.

Unfortunately, PixelYourSite version 10.1.1.1 has been found vulnerable to a critical security flaw. Unvalidated user input is used directly in the PHP unserialize function, located in the myapp/modules/facebook/facebook-server-async-task.php file. This vulnerability has been assigned Common Vulnerabilities and Exposures (CVE) ID CVE-2025-0769.

The vulnerable code lies within myapp/modules/facebook/facebook-server-async-task.php

<?php
// Imports ...

// Security Check
if ( ! function_exists( 'some_secure_function' ) ) {
    exit;
}

// ...

function processData() {
    $requestData = $_POST['data'];
    $unserializedData = unserialize( $requestData ); // <--Issue lies here, data is not sanitized

    // Do some processing
}

As we can see, the $_POST['data'] variable containing the user's input is directly passed to the unserialize function without any form of validation or sanitization. This issue may lead to remote code execution by an attacker crafting a POST request that includes a malicious payload.

Exploit Details

The vulnerability in PixelYourSite can be exploited by sending a specially crafted POST request to the server hosting the plugin. The exploit consists of the following steps:

1. Craft a PHP object with a malicious payload. For instance, using the GuzzleHttp\Psr7\FnStream class (available in the Guzzle library), which may already be installed on the target server:

'close' => function () {

// Add malicious code here
// e.g. eval($_GET['shell']);

]

);

'data' => urlencode(serialize($payload)),

];
// Submit this request to the vulnerable server

`

3. If successful, the server will execute the malicious payload during the unserialize processing, allowing the attacker to execute arbitrary code on the server.

Mitigation Steps

For those who are using the PixelYourSite plugin, it is strongly recommended to update the software to the latest version. The vulnerability is fixed in version 10.2.2. An update will ensure that the flawed unserialize function usage is corrected, securing your server and customer data from potential attacks.

Regularly monitor server logs and scan your server for vulnerabilities.

In conclusion, taking immediate and proactive steps to address CVE-2025-0769 will ensure that your PixelYourSite installation remains safe from exploitation. Upgrading to the patched version and applying best security practices can help prevent potential data breaches and maintain the trust of your customers.

Stay updated on this vulnerability by regularly checking the following references

- Official CVE-2025-0769 page
- PixelYourSite Changelog for updates and patches
- OWASP Secure Coding Guidelines for guidance on best security practices

Timeline

Published on: 02/28/2025 20:15:46 UTC